Electronic keyboards and other electronic musical instruments provided with an automatic rhythm, chord or other accompaniment function are widely known. In such an electronic keyboard instrument, automatic accompaniment pattern data for each of rock, waltz and other rhythms is previously stored in a ROM or other storage device. The automatic accompaniment pattern data can be read for repeated performance.
The known electronic keyboard instrument is also provided with a MIDI terminal for transmitting and receiving keyboard performance information or automatic accompaniment information. By transmitting and receiving information to and from external instruments having a sound source and a sequencer, various instruments can be concurrently played. The MIDI referred to herein is a unified standard of communication procedure for electronic instruments.
Automatic accompaniment pattern data have recently achieved fairly realistic performance capabilities, by diversifying the sound source control information and other performance information and thereby enlarging the quantity of information for use in a performance. The sound source control information includes the information used for modifying fixed tones with operating elements other than the keyboard. Specifically, pan information for varying the position of sounds in the left to right direction, balance information for balancing sound volume in the left to right direction, expression information for accenting sounds having programmed volumes and the like are included.
Because of such vast performance information, when the external sound sources are sounded or sound is recorded into the external sequencer, by converting the automatic accompaniment pattern data into a MIDI signal and serially transferring the signal, for example, the performance of the external sound sources is delayed as compared with when the performance is created by deriving the sound signal directly from the automatic accompaniment pattern data without converting the data into a MIDI signal.
The MIDI signal character is composed of eight bit. The speed of transferring each bit is defined as 31.25 kbaud. As the quantity of information for use in the performance is increased, the number of MIDI signal characters is increased. Therefore, it takes time for the automatic accompaniment pattern data to be serially transferred. For this reason, the performance of external sound sources is executed with a delay. Especially, concurrency between the performance of a performing system transmitting a MIDI signal and that of a performing system receiving a MIDI signal is impaired.